Imprinting attachment for sheet feeding devices



A. F. GRASSO Dec. 13, 1960 IMPRINTING ATTACHMENT FOR'SHEET FEEDING DEVICES 3 Sheets-Sheet 1 Filed Sept. l0, 1956 INVENTOR. ,4u-'6in @Mn/fs Hasso LMr'SQVQL/IL A. F. GRASSO Dec. 13, 1960 IMPRINTING ATTACHMENT FOR SHEEI` FEEDING DEVICES Filed Sept. l0, 1956 3 Sheets-Sheet 2 De 13, 1960 A. F. GRASSO 2,963,963

Ii/FRIN'I'ING` ATTACHMENT FORAJSHEET FEEDING DEVICES Filed sept. 1o, 195e 3 Sheets-Sheet 5 United States Patent O IlVIPRINTlNG ATTACHE/ENT FOR SHEET FEEDTNG DEVICES Alfred Francis Grasso, 11 Haypath Road, Bethpage, N.Y.

Filed Sept. 10, 1956, Ser. No. 608,759

9 Claims. (Cl. 101-80) The present invention relates to a numbering, dating or similar imprinting attachment for use with a lithograph or similar press or sheet utilization device, and more particularly to an attachment of this character for use in connection with sheet feeding mechanism by which a stack of sheets is `fed upwardly, one or more numbers being imprinted on the top sheet of the stack just prior to the inst-ant when the top sheet is seized by the sheet feeding mechanism and delivered to the printing instrumentalities of the press or other utilization means.

When serial numbers lare to be imprinted on a series f printed sheets it has heretofore been customary either to employ la press specially equipped with numbering heads or to imprint the num-bers as a separate operation. In one case a relatively costly press is required and in the other, the cost of the separate numbering operation adds materially to the cost of the printing job.

The present invention overcomes these disadvantages by. printing a serial number or other identifying indicia on the top sheet of a stack of sheets which is being fed upwardly by conventional sheet feeding mechanism. The numbering attachment is driven in synchronism with the sheet delivery mechanism, a single number or plurality of numbers being imprinted on the top sheet by one or more conventional self-inking numbering heads. The numbering heads move down into printing engagement with the top sheet during the interval beginning when a new top sheet has vbecome accessible and ending prior to the time when the top sheet is seized by the usual sheet delivery mechanism and forwarded either to printing means or to some other form of utilization device for the numbered sheets.

An object of the invention is to provide Ia numbering or similar special imprinting attachment for use with sheet feeding and delivery mechanism, the attachment being readily removed when not required or conveniently positioned on the sheet feeding mechanism whenever desired.

Another object of the invention is to provide an attachment of this character in which a uniform printing pressure is applied in the course of each successive operation of each imprinting or numbering head.

A further object of the invention is to provide an attachment of this character wherein each imprinting head is adjustable to print at any desired position on each sheet.

A feature of the invention resides in the provision of means for tilting the numbering or imprinting heads from their vertical operating position to a horizontal position. When the numbering heads are thus tilted, the printing wheels may be set to any desired starting num-ber or the type may be changed before the beginning of a run.

Another object of the invention is the provision of an ink pad for the numbering machines which provides for the storage of a materially greater quantity of ink than is possible in the case of the usual hand numbering machine for oice use.

Briey, the invention comprises a supporting frame which is mounted on the printing press or other device,

r"ice the position of the frame being adjustable in the direction of individual sheet removal and delivery. The frame carries supporting bars on which guide members are mounted, the guide members being adjustable transversely of the direction of sheet delivery. A numbering or imprinting machine holder is vertically reciprocable in each guide member. Each holder is connected to a common horizontally extending oper-ating rod. Adjustable linkage connects the operating rod to tbe sheet withdrawal and forwarding mechanism so that the numbering or imprinting machines move downwardly and upwardly in correctly timed relationship with respect to the removal of the top sheet rand the accessibility of the next underlying sheet as it becomes the top sheet. Means are provided for moving the numbering or imprinting machine holders. upwardly in their respective guide members beyond their normal range of travel whereby the machines may be swung outwardly to set the numbering or imprinting wheels. The numbering or imprinting machines are connected to their respective holders through pre-stressed springs which control the printing pressure and which compensate for slight variations in the level of the top sheet as the upwardly fed stack of sheets Ibecomes depleted.

Various other objects, advantages and features of the invention will become apparent upon reading the following specication together with the accompanying drawing forming ya part hereof.

Referring to the drawing:

Figure l is an end elevational View showing an -attachment in accordance with the invention mounted on a printing press, looking in the direction of sheet withdrawal and forwarding.

Figure 2 is an enlarged fragmentary sectional view in side elevation taken along the line 2-2 of Fig. l, looking in the direction of the arrows and illustrating means for removing or replacing one of the two guide members and its associated mechanism.

Figure 3 is an enlarged plan sectional view taken along the line 3-3 of Fig. l.

Figure 4 is a side elevational View on a reduced scale and showing the adjustable linkage together with its driving connection to operating mechanismV of the Sheet delivery and forwarding instrumentalities.

Figure 5 is a side elevational view on a further reduce scale illustrating diagrammatically one of the imprinting heads swung out to permit the manual setting of its numbering or printing wheels.

Figure 6 is a plan view of a printed sheet showing two mutually inverted numbers printed symmetrically on opposite sides of a central dividing line, the printed sheetv being subsequently cut along the dividing line to form two separate individually numbered printed forms or the like with the numbers in the same position on each half of the cut sheet.

Figure 7 is lan enlarged view in side elevation, partly 'broken `away to illustrate details of construction and showing the attachment in printing position in which the numbering or imprinting heads are at the limit of their downward travel...

Figure 8 is a view similar to Fig. 7, except that the parts of the attachment are so positioned that the imprinting machines are at the normal upper limit of their travel.

Figure 9 is a sectional view in side elevation taken along the line 9--9 of Fig. l, looking in the direction of the arrows and showing one of the numbering or im? printing machines pressed into printing engagement with the top sheet of a stack of sheets.

Figure 10 is a sectional view of an ink pad.

Referring to Fig. l, the attachment comprises a frame 10. The frame 10 has a horizontally extending cross- .Y Y w 3 bar portion 11 which is supported by two integrally formed vertical leg portions 12 and 13. At the outer side of its lower end, the leg 12 carries a guide block Y14'which is xedly secured thereto. Spaced below the guide block 14 and also xedly secured to the Vleg 12 is a curved supporting arm 15. The arm 15 comprises a horizontal portion 16 which extends in spaced parallel relationship to the guide block 14 and a downwardly curvedfree end 17. A xed horizontal supporting rod 19 is slidably received between the guide block 14 and the horizontal portion 16 of curved arm 15. The fixed rod 19 is of square cross section and one end portion is xed to the frame (not shown) of the printing press or other device with which the attachment is used.

The outer side of the other leg 13 of frame 10 carries vertically spaced guide blocks 20 and 21-which are fixed secured to its lower end. Y A ixed horizontal supporting rod 22,V of squareV cross section, is slidably received between the guide blocks 20 and 21. One end portion of the fixed rod 22 is xed to the frame (not shown) of the press like the other rod 19. The two rods 19 and 22 extend parallel to each other at opposite sides of a stack 24 of paper sheets. The entire frame 10 may thus be moved along the parallel rods 19 and 22 for locating it at any desired position along the direction of sheet forwarding from the stack 24. The frame 10 may be locked in such position of adjustment by tighting set screws 25 and 26 threaded in guide blocks 14 and 20, respectively.

An upper transverse supporting rod 28 extends between frame legs 12 and 13. A similar lower transverse supporting rod 29 extends parallel to upper rod 28 between the legs 12 and 13. They lower rod 29'is vertically spaced from the upper rod 28. Two complete numbering units 30 and 31, for example, are shown mounted on the rods 28 and 29. One end of upper rod 28 extends freely through a hole 31 in -frame leg 12. One end of lower rod 29 similarly extends freely through a hole 32 formed in frame leg 12. The other ends of the rods 28 and 29 extend through similar holes formed in the frame leg 13, the other end of the lower rod 29 being threaded and secured against longitudinal movement by cooperating lock nuts 34 disposed on opposite sides of frame leg 13.

A pivot rod 35 extends between frame legs 12 and 13 parallel to the supporting rods 28 and 29. The pivot rod 35 is secured against longitudinal movement by cotter pins 36 and washers 37 located adjacent to the outer sides of the legs 12 and 13. The pivot rod 35 is freely rotatable Vin the frame legs 12` and 13. An actuating rod 39 extends parallel to pivot rod 35 and is connected to the pivot rod 35 at one end by a triangular plate 40 and at the other end by an arm or link 41. The arm 41 is shown pinned tothe pivot rod 35 at 42. The triangular plate may likewise be fixed to the pivot rod 35 to increase the torsional rigidity of the actuating assembly 35, 39, 40, 41. A collar or spacer 44 is mounted on pivot rod 35 between triangular plate 40 and the inner side of frame leg 12. Another collar or spacer 45 is mounted on the pivot rod 35 between the arm 41 and the inner side of frame leg 13. The actuating rod 39 may thus swing in an arcuate path about the pivot rod 35 as an axis, the actuating rod 39 remaining parallel at all times to the pivot rod 35 and to upper and lower supporting rods 28 and 29. Y Y Two imprinting or numbering assemblies designated generally as 47 and 48, resp,ectively, are mounted on the upper and lower rods 28 and 29. The assembly 47 comprises two vertical side plates 50 and 51 rigidly interconnected by aV cross-plate 52. The cross-plate 52 tits between the upper and lower supporting rods 28 and 29. The thickness ofcross-plate 52 is somewhat less than the equal diameters of the supporting rods 28'aud 29.

l'herupper andk lower edges of cross-plate 52 engageV YA"tapestries against the lower and upper sides, respectively, of rods 28 and 29.

A bolt 54 carried by the cross-plate 52 extends freely through a clamping plate 55. Clamping plate 55 has curved upper and lower end portions 56 and 57. A wing nut 59 is threaded on bolt 54. When tightened, the wing nut 59 presses the upper curvey end 56 of clamping plate 55 against ythe upper rod 28 forcing the rod 28 downwardly against the upper side of cross-plate 52. The lower end 57 of clamping plate 55 similarly forces the lower rod 29 upwardly against the lower side of crossplate 52. This secures the numbering assembly 47 securely to the supporting rods 28 and 29. When the wing nut 59 is loosened, the numbering assembly 47 may be moved along the rods 28 and 29 transversely of the direction of sheet delivery to any desired position, except as limited by the other numbering assembly 48. Tightening of wing nut 59 locks the numbering assembly 47 in such desired position of adjustment. The other numbering assembly 48 is similarly provided with a clamping plate 50 and a wing nut 61.

The side plates 50 and 51 of assembly 47 have con- Y fronting vertical grooves 63 and 64 formed therein. The

upper ends of side plates 50 and 51 are made oblique for purposes which are later to be described. A vertically reciproc-able carrier 65 is mounted between the side plates 5t) and 51. The carrier 65 is provided with four guide pins 67 to 70. The guide pins 67 and 69 are vertically spaced and are freely slidable in the groove 63 of side plate 50. The pins 68 and 70 are similarly slidable in groove 64 of side plate 51. Thus, so long as the pins 67-to 70 remain engaged in the grooves 6.3 and 64, the carrier 65 is free to move vertically guided in a path dened by the grooves 63 and 64. The pins 67 and-68 are axially aligned andthe pins 69 and 70 are likewise axially aligned on an axis spaced below and parallel to the axis of alignment of pins 67 and 68. The numbering assembly 48 is similarly provided with a vertically reciprocable carrier 72.

A double-ended bracket 73 is mounted on the carrier 65 by screws 74. The ends of bracket 73 are provided with integrally formed laterally spaced ears 76 and 77. A stirrup-shaped link member is rotatably and freely slidably mounted on the actuating rod 39. The Vstirrup 79 comprises downwardly extending legs 80 and 81 which are pivotally connected to the bracket ears 76 and 77 by pins 83 and 84, respectively.

As may best be seen Vin Fig. -2, provision is made for disconnecting the stirrup 79 from the actuating rod 39 when it is desired to remove the entire numbering assembly 47 from the attachment.

and longitudinally slidably connected to the stirrup-V shaped link 79, being received in the cooperating oppositely opening notches 86, 92 and 87, 93. Movement of actuating rod 39 about pivot rod 35 will therefore cause vertical movement of carrier 65.

The numbering assembly 48 is similarly provided with a stirrup-shaped link member 95 for vertical reciprocation of its carrier 72. The link member 95 of number# ing assembly 48 is not disconnectable, however, because there is no need to remove both numbering assemblies 47 and 48 simultaneously from the attachment. With numbering assembly 47, removed, the'numbering assembly 48, if used alone, is afforded a wider range of adjustment along the supporting rods 28 and 29 than would be available if it were left mounted in therattachment andsimply made inoperative by other means.

The legs SG and 81 of stirrup 79 have notches 86 and 87'formed in their re-v Referring to Fig. 3, the carrier 65 of numbering as'- sembly 47 is provided with a square-shanked bolt 97 having a wing nut 98 threaded thereon. A seating plate 99 is fixed to carrier 65 and has a shallow vertically eX- -tending channel formed therein in which a numbering machine supporting block 100 is received and maintained vertically positioned. The supporting block 190 is clamped in the seating plate 99 by a dog 102 which is tightened by wing nut 98. When the dog 102 is released by loosening wing nut 98, the supporting block 100 may be adjusted vertically and clamped in a desired position of adjustment by tightening wing nut 9S.

The numbering assembly 48 is provided with a similar dog 103 which may be tightened by a wing nut 1415 to hold a numbering machine supporting block vertically positioned in a seating plate. 107 Xed to carrier 72. The supporting block 106 is deeper than the block 100 and bolt S upon which the wing nut 105v is threaded is accordingly somewhat longer' than the bolt 97 of the other numbering assembly 47. A vertically extending numbering machine operating shaft 110 is freely slidably disposed in the supporting block 100 of numbering assembly 47 and a similar shaft 111 is slidable in the block 106 of numbering machine assembly 48. The shaft 111 is located somewhat forwardly of the shaft 110, as shown in Fig. 3, so that the numbers willv be printed on separate spaced lines 112 and 113.

At their lower ends, the shafts 110 and 111 carry conventional numbering machine heads 115 and 116, respectively, of the usual self-inking type. The numbering machine heads, except for the longer shafts 110 and 111, are similar in all respects to hand operated numbering machines for oice and general use, such as a Model 49 numbering machine manufactured by The Roberts Numbering Machine Company of700 Jamaica Avenue, Brooklyn 8, N.Y. Each numbering head comprises the usual apertured plate 117 which presses against the top sheet of the stack 24 when printing, the printing wheels engage the sheet through the window (not shown) of the apertured plate 117. The plate 117 isA fixed to the bottom of an inverted U-shaped frame 119 which has a bushing 120 fixed thereto centrally of its top. The shafts 110 and 111 extend slidably through the bushings 1213 for actuation of the numbering mechanism, this action taking -place after the plate 117 has moved downwardly into engagement with the top sheet of the stack 24.

Each of the shafts 110 and 111 is coaxially surrounded by a stiff prestressed helical compression spring 121 which presses downwardly on a washer 123 longitudinally fixed on its respective shaft 110 or 111, and upwardly against the bottom surface of its associated supporting block 100 or 106. Downward movement of each of the shafts 110 and 111 in blocks 100 and 196, respectively, is limited by lock nuts 124 threaded on its upper end, The lock nuts 124 are pressed against the top surface of supporting block 100 or 106 by the stiff compression spring 121. There is a relatively weak helical compression spring 125 coaxially surrounding each shaft 111, 112 and which is ensleeved in each of the bushings 120 below the stiff spring 121. Each weak spring 125 presses upwardly against the washer 123 and downwardly against the U-shaped frame 119. The weak springs 125, which act on the under sides of the washers 123, form a part of the standard numbering machine mechanism and serve as retractile springs for completing actuation of the numbering mechanism by causing downward movement of the frame 119 on its associated shaft 110 or 111, after the completion of each impression. The sti springs 121, acting on the upper sides of the washers 123, serve to apply a positively predetermined printing pressure to the shafts 110 and 111. This pressure is transmitted to and acts between the type wheels and the paper during each impression. The stiff springs 121, being prestressed, further serve to compensate for minor variations in the vertical position or level of the top sheet of paper during upward feeding movement of the stack 24.

Eachv of the blocks and 106 has a transverse slot 127 formed therein and extending diametrically from opposite sides of the shafts 111 and 112, respectively. Each slot 127 extends vertically downwardly to a limited depth in its associated block 100 or 106 and is open at its top. Each of the shafts and 111 carries a transversely extending guide pin 128 which is vertically slidable in the slot 127. The guide pins 12S prevent rotation of the shafts 111 and 112 in the blocks 100 and 106, respectively, and thus assure that the line of printing of each numbering head will remain fixed at the cor rect angle during operation of the device.

A stud 129 is fixed to the triangular plate `40 and extends laterally beyond the leg 12 of frame 10. The stud 129 comprises a shank portion 131. The shank 130 is connected to the pivot `shaft 35 by a link 132 to reduce bending stresses on the stud 129. A triangular rocker plate 133 is pivoted to the free end of the curved portion 17 of supporting arm 15 by a -stud 135. The rocker plate 133 is connected to the triangular plate 40 by a link 136. A drive plate 137 is connected to the rocker plate 133 by a pivot pin 139.

A drive rod 140 is clamped to the drive plate 137 by a dog 141. The dog 141 is tightened against the drive rod 140 by means of a bolt 143 and a wing nut 144. Struck up ears 145 formed in drive plate 137 engage the sides of drive rod 140 and prevent it from rotating with respect to drive plate 137. The longitudinal position of drive rod 140 with respect to drive plate 137 may be adjusted by loosening the wing nut 144. The drive rod 140 may then be slid under dog 141 to a desired position of adjustment and secured in such position by tightening wing nut 144'.

Referring to Fig. 4, a typical lithograph press (not shown) with which the numbering attachment may be used comprises a cam 147 which is pivoted to the press frame at 148. The cam 147 is operatively associated with the sheet forwarding and delivery mechanism of the press. The cam 147 is rotated through a limited arc abo-ut its pivot 148 by means of a pitrnan 149 connected to a pivot pin 150 on cam 147 and an eccentric pin 151 mounted on a wheel 152. One end of drive rod 140 is also connected to pivot pin 150. The wheel 152 is mounted on a shaft 153. The shaft 153 makes one revolution for each sheet withdrawn from the stack 24. The timing or phasing of pin 151 is so adjusted with respect to the sheet delivery cycle that pitman 149 reaches its limit of movement toward the right las shown in Fig. 4 just prior to withdrawal of the top sheet from stack 24 by the usual suction or equivalent devices of the sheet delivery mechanism. The stack 24 is supported by brackets 155. The brackets 155 move upwardly as sheet feeding progresses so that the top sheet of the stack 24 is maintained at the same level or fixed vertical position as the stack becomes progressively depleted.

Referring to Figs. 7 and 9, the rocker plate 133 is in the same position in which it is shown in Fig. 4, the pitman 149 and the drive rod 140 being at their respective limits of movement toward the right. tion, the actuating rod 39 is at its limit of travel and the stirrup-shaped link member 79 is nearly vertical so that a toggle action is obtained in applying pressure to the printing wheels of the numbering assembly 47, this pressure being applied through the stiff compression spring 121. When the pitman 149 and drive Irocl 140 are at their leftward limits of travel, the parts are in the position shown in Fig. S, the numbering heads 115 and 116 (which are not visible in this figure) both being raised slightly above the top sheet of the stack 24. -T his raising of the numbering heads takes place in timed relationship so that the printing is completed and the plates 117 disengaged from the top sheet just before the sheet delivery mechanism commences to withdraw the top sheet from In this posi-v accesos 7 'stack 24 for forwarding to the printing'instrumentalities ofthe press. Y, Y p Y p W As shown in Fig'. 8, an arm 156 is secured to the frame leg 12 by a pivot stud 157. A torsion spring'159 urges arm 156 in a counterclockwise direction as viewed in Fig. 8 so that it presses upwardly against a stop screw 160. Ordinarily, the limit of counterclockwise movement of triangular plate 40 is as shown in Fig. 8. However, the corner 161 of triangular plate 40 may be forced' past the arm 156, so that the carriers 65 and 72 rise above their normal upper limits of'travel. When so raised, the upper guide pins 67 and 68 of carriage 65 rise above the upper ends of grooves 63 and 64 so that the upper pins 67 and 68 are free to move rearwardly'as permitted by the sloping upper ends of side plates 50 and 51, the lower pins 69 and 70 then acting as pivots instead of guide pins. Under these conditions, the entire reciprocable carrier `65 may be swung into the position shown in Fig. 5. In this position, the type wheels are accessible and may be moved to any desired starting number by means of a wooden pick or the like while the U-shaped frame 119 is held so that the numbering mechanism is partially actuated. The starting numberl may be similarly preset in numbering assembly 48. It is particularly advantageous to be able to swing the numbering-heads out to the position shown in Fig. so that the starting number may be preset since this may be done without disturbing the adjustment of any other portion of the numbering attachment. After the number has been preset, the numbering head is swung back so that upper guide pins 67 and 68 are again in alignment with the grooves 63 and 64. The triangular plate 40 is then rotated in a clockwise direction and its corner 161. is again forced past arm 156 to restore the partsto the position shown in Fig. 8. During number setting, it may be desirable to disconnect the drive rod 140 from pivot pin 150. Alternatively, the position of dog 141 may be marked on drive rod 140 and wing nut 144 loosened. After presetting theV desired starting numbers, the drive rod 140 and dog 141 may be restored to their marked relative positions and the wing nut 144 retightened.

There is a wide range of adjustment of the frame in the direction of sheet feeding and a wide range of transverse adjustment of the numbering assemblies 47 and 4S along the upper and lower supporting rods 28 and 29. Itis thus possible to print a serial number in practically any desired position on each sheet before it is forwarded to the press.

An example of the type of work which may be produced with a numbering attachment of this kind is illustrated in Fig. 6. A sheet of paper 163 is shown with ltwo serial numbers 164 and 165 printed on opposite sides of the center line 166. The serial number 164 is inverted with respect to the center line 166. The spacing on opposite sides of the center line 166 is obtained by the use of dilerent supporting blocks 100 and 106 as shown in Fig. 3. In this manner, a double form may be printed around the serial numbers 164 and 165, one half of the form being inverted with respect to the other half and with the center line 166 dividing the two forms. After printing has been completed, a stock of printed forms is cut along the center line 166 to produce two stacks of identical forms in which two forms are printed' and serially numbered at each operation of the press. In order to provide proper sequence in the serial numbers, one of the numbering heads may be preset to start half way through the complete sequence of serial numbers to" be used, and the other set to start at the beginning of the sequence.

It has further been found to be advantageous Vto use a form of ink pad which is diiferent from lthe usual felt pad used in hand operated oce machine. As shown in Fig. 10, the ink pad is mounted in the usual metal holder 168 of channel-shaped cross section. The holder 168 Vis removably mounted in the numbering head to facilitate re-inking. The mounting means are conventional and Vare therefore not illustrated. The pad is pressed against the type wheels each time that they are retracted after the printing of an impression. Thepad shown comprises an ink-storage base layer 169 formed of sponge rubber andv an ink-applying layer 170 formed of felt.' In this way the greater ink storage capacity of the sponge rubber is obtained without impairing the desirable ink distributing properties of the felt. Because of drying, this type of inkpad will not ordinarily be desirable for use in hand operated oce machines. However, in the present printing press attachment where production runs are involved, a large ink storage capacity is essential in order to avoid stopping the press for re-inking.

While I have shown and described what I believe to be the best embodiments of my invention, it will be apparent to those skilled in the art that many changes and modifications may be made in the specific embodiments disclosed, all within the spirit and scope of the invention as defined in the appended claims.

I claim: Y Y

l. An imprinting attachment for use with cyclically operative sheet forwarding means, said forwarding means including xed supporting means, delivery means for withdrawing and forwarding successive top sheets from a stack of sheets, and means for raising said stack for maintaining the top sheet thereof at a fixed predetermined level during the progressive depletion of said stack, said attachment comprising =a frame extending above said stack, said frame being adjustably connected to said xed supporting means for movement in the direction of Ysheet withdrawal of said forwarding means, supporting rod means carried by said frame and extending transversely of said sheet withdrawal direction, guide means carried lby said rod means,

means for locking said guide means in a desiredppositonV of adjustment along said supporting rod means, a vertically recprocable carrier disposed in said guide means, an imprinting machine mounted on said carrier for reciprocation therewith, said machine applying an impression to said top sheet during the lowermost portion of the movement of said carrier, a movable actuating rod extending parallel to said supporting rod means, means constraining said actuating rod to remain parallel to said guide rod means. during lateral movement of said actuating rod means, link means connecting said 1actuating rod to said carrier for causing vertical movement of said carrier, and driving means connecting said actuating rod to said forwarding means for imparting cyclical lateral movement to said actuating rod, said driving means causing said machine to apply said impression to a particular sheet of said stackV during the interval while said particular sheet has rst become accessible for printingv by the withdrawal of previously overlying top sheet and prior to the Vtime when said particular sheet, then being the top sheet, is VYwithdrawn and forwarded by said delivery means.

2. An attachment Iaccording to claim 1, in which said machine is vertically elongated and Vincludes printing' means which are manually settable and which are accessible for the setting thereof only from .the lower end of said machine, and wherein said guide means comprises means for partially releasing said carrier for pivotal movement therein upon displacement of said carrier in said guide means beyond the normal limits of its reciprocatory movement, said pivotal movement permitting said lower end of said machine to be positioned for access to Vsai printing means for setting the same. v

3. An attachment according to claim 1, further comprising prestressed spring means interposed betweenV said carrier and said machine Vfor providing a positively predetermined printing pressure during said applying of /said impression. y Y

4. An imprinting attachment for use with cyclically operative sheet forwarding means, said forwarding meansY including xed supporting means, delivery means for` withdrawing and forwarding successive top sheets from a stack of sheets, and means for raising said stack for maintaining the top sheet thereof at a fixed predetermined `level during the progressive depletion of said stack, said `attachment comprising a frame extending above said stack, said frame being adjustably connected to said ixed supporting means for movement in the direction of sheet withdrawal of said forwarding means, means for locking said frame in a desired position of adjustment, a pair of spaced parallel supporting rods extending across said frame transversely of said sheet withdrawal direction, the ends of said rods being supported by said frame, a plate slidably interposed between said rods, clamp means for pressing said rods yagainst said plate and securing said plate iixedly to said rods, a pair of spaced guide members carried by said plate, each of said guide members having a Vertical groove formed therein, a vertically movable carrier guided by said grooves, an `actuating rod extending parallel to said supporting rods, means connecting said actuating rod to said frame for pivotal movement about an axis parallel to said supporting rods, link means connecting said actuating rod to said carrier, drive means connecting said actuating rod to said forwarding means for cyclical movement therewith, said cyclical movement causing vertical reciprocation of said carrier, and a selfinking imprinting head mounted on said carrier for movement therewith, said head printing an impression on each successive top sheet during the course of the lowermost portion of said reciprocatory movement of said carrier.

5. An attachment according to claim 4, in which said carrier comprises upper and lower guide members, one upper and one lower guide member being engaged in each vertical groove, said lower guide members being aligned to provide a horizontal pivotal axis of rotation for said carrier with respect to said frame, said carrier being displaceable upwardly beyond its normal limits of travel to free the upper ones of said guide members each from its respective groove thereby permitting rotation of said carrier about said horizontal axis for access to the lower end of said imprinting head.

6. An attachment according to claim 5, in which said head comprises a vertical shaft, downward displacement of said shaft causing printing operation of said head with a pressure of impression determined by the amount of downward pressure on said shaft, said attachment further comprising a supporting block slidably disposed on said vertical shaft, stop means limiting downward movement of said shaft in said block, resilient means pressing said vertical shaft downwardly in said block, said resilient means determining said pressure of impression, and means connecting said supporting block to said carrier, said last-named means permitting adjustment of the vertical position of said block with respect to said carner.

7. An attachment according to claim 5, in which said link means is stirrup-shaped with leg portions pivotally connected to said carrier and pivotally and slidably connected to said actuating rod.

8. An attachment of the class described, comprising supporting means for a sheet to be imprinted, guide means having spaced confronting vertical grooves, a carrier, four guide pins fixed to said carrier and engaged in said grooves, said guide pins comprising two upper pins and two lower pins, one upper pin and one lower pin being engaged in each of said grooves, said lower pins being aligned to del-lne a horizontal axis of rotation for said carrier in said guide means, means for producing vertical reciprocatory movement of said carrier in said guide means, said carrier being displaceaple upwardly beyond the normal limits of said reciprocatory movement to free the upper ones of said pins from said grooves thereby permitting said carrier to be rotated about said horizontal axis, and an elongated self-inking imprinting device mounted on said carrier for movement therewith, said imprinting device comprising manually settable printing means which are accessible for the manual setting thereof only through the lower end of said imprinting device, said printing means acting through said lower end of said imprinting device to apply a printed impression to said sheet during the lowermost portion of said reciprocatory movement, said printing means being accessible through said lower end without displacing said sheet by rotating said carrier about said horizontal axis.

9. An imprinting attachment for use with cyclically operative sheet forwarding means, said forwarding means including xed supporting means, delivery means for withdrawing and forwarding successive top sheets from a stack of sheets, and means for raising said stack including means for maintaining the top sheet thereof at a xed predetermined level during the progressive depletion of said stack, said attachment comprising a frame extending above said stack, said frame being adjustably connected to said iixed supporting means, a vertically reciprocable carrier disposed in said frame, guide means for said carrier, actuating means disposed in said frame and connected to said carrier for producing reciprocation thereof, a vertically elongated imprinting machine xed to said carrier, said machine including manually settable printing means accessible only from the lower end of said machine, said machine applying an impression to said top sheet during the lowermost portion of the travel of said carrier, said carrier being displaceable in said guide means in one direction beyond its normal limits of reciprocatory travel in said guide means, said carrier when displaced beyond said normal limits being partially freed from said guide means to be pivotable in said guide means for access to said printing means for setting said printing means, and operating means connecting said actuating means to said delivery means for operation therewith, said operating means causing said machine to imprint said impression to a particular sheet during the interval while said sheet has become accessible for printing by withdrawal of the previously overlying top sheet and prior to the time when said particular sheet, then being the top sheet, is withdrawn and forwarded by said delivery means.

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